FINAL PREPARATIONS: 1968

Picking Landing Sites

Landing site evaluation had begun as soon as photographs from the first
Lunar Orbiters became available. [see Chapter
6] By March 1967 MSC's Lunar and Earth Sciences Division had
prepared a short list of candidate sites,* which it presented to the Apollo Site
Selection Board. Operational considerations predominated at this stage
of planning; the sites were all within the "Apollo zone of
interest" (5 degrees north to 5 degrees south latitude, 45 degrees
east to 45 degrees west longitude) and appeared from the Orbiter
photographs to be comparatively level and smooth. MSC recommended that
sites for the first landing be chosen from that list by August 1. The
board accepted that recommendation.61
For the rest of the year the Apollo Site Selection Board worked
steadily, with input from Bellcomm, the Jet Propulsion Laboratory, the
U.S. Geological Survey, and the Group for Lunar Exploration Planning,
evaluating additional photographs from Lunar Orbiters as they became
available.** Meanwhile MSC
continued to study the operational constraints of its chosen sites;
planners were mainly concerned with slopes and irregularities in the
terrain along the approaches to the sites, which could interfere with
the lunar module's landing radar. The data necessary to make the final
choice of sites (principally topographic maps) were slow in coming,
however, and MSC could not meet the August 1 date it had proposed.62 Instead the site selection board met at
Houston on December 15 to decide on sites for the first two missions and
to lay out a schedule for future activities.

MSC presented the results of its studies on approach paths, which showed
that all the "Set B" sites were acceptable. Simulations showed
that the lunar module's landing radar could guide the spacecraft to a
landing at any of the eight sites. A considerable part of the discussion
dealt with the number of sites to be retained in planning for each
mission. At this stage no one could be sure that every mission would be
launched on time. If a technical malfunction caused a countdown to be
stopped, up to 66 hours' delay in launching might be necessary, in which
case a more westerly landing site would have to be substituted for the
original. This entailed complications in other aspects of mission
preparation - it required the astronauts to become familiar with three
different landing approaches and geologic areas, for example, and
increased the requirements for maps and other data - but the alternative
was to postpone the launch for at least a month.63

After summing up the detailed evaluations, John E. Eggleston, chief of
MSC's Lunar and Earth Sciences Division, recommended five of the best
sites ("Set C") for the first landing mission and another six
for the second, which the board approved.64 Eggleston and Wilmot Hess, chief of MSC's
Science and Applications Directorate, then directed the board's
attention to the need to begin evaluating sites for the third and
subsequent missions. Landing areas topographically different from those
already chosen should be examined. Evaluation of highland sites in or
near the Apollo zone should be started. Board chairman Sam Phillips
agreed in principle that the third mission could be more ambitious, but
he advised planners to stay on the conservative side for the time being
and look for science targets in the areas covered by the Set B sites. A
U.S. Geologic Survey representative suggested that in some cases
shifting the landing point only a few kilometers within a selected area
would bring the astronaut-explorers within walking distance of some
scientifically interesting features. He also pointed out that if the
first landing was made in an eastern mare the second should be targeted
to a western one, since maria showed different characteristics in the
two regions.65

From early 1968 onward the site selection teams would get only limited
additional lunar photography, since after the fifth*** no more Orbiters would be flown. Orbiter
photographic coverage, however, was not comprehensive; it did not cover
every interesting site with sufficient resolution to permit detailed
evaluation. Until the middle of 1967 the Office of Manned Space Flight
was planning to fly an advanced lunar mapping and survey system that
would furnish more detailed coverage of a greater portion of the lunar
surface; but in August its potential value to Apollo was judged to be
marginal and its further development was canceled to save money.66 The following March, however, Sam Phillips
noted a continuing need for lunar photography and asked MSC to consider
how it might be provided by astronauts in lunar orbit on scheduled
Apollo flights.67 Houston enumerated
several types of cameras and film that could be useful in site selection
and in lunar cartography, and scientific interpretation as well.68 Planning was started for a considerable
amount of lunar surface photography, including candidate sites for
future landings, to be conducted on every manned lunar mission.

* "Landing sites," as
somewhat loosely used in the following discussion, corresponds more
nearly to the "landing areas" previously mentioned. [Chapter. 6] However, within the larger areas
studied, MSC evaluators did examine several specific landing ellipses -
"sites," in the sense that term was used before.

**Lunar Orbiters III,
IV, and V, launched on Feb. 4, May 4, and Aug. 1,
1967, all returned photographs used in Apollo landing site selection.
Four more Surveyors were landed by early 1968 as well; although they
were mainly equipped for scientific studies, they also provided Apollo
with useful data on properties of lunar soil.